February 2010 Monthly RVL Report

Cattle

Athlone reported on two bovine abortion investigations (different farms) where placenta was submitted along with the foetus. In both cases histological examination of the placenta revealed intracellular basophilic inclusions within the trophoblast cells of the cotyledons with mild to moderate suppurative placentitis. These findings prompted further testing. On the first farm the foetal membranes from two aborting cows tested positive for Chlamydophila abortus specific DNA and one of these cows tested sero-positive in a C.abortus antibody. There was no recent history of contact with sheep. On the second farm two cows had aborted and one tested positive for specific antibody in a Coxiella burnetti test. C. burnetti is the aetiological agent of Q fever. Seroconversion is reported to be very variable in cows aborting due to Q fever. Both Ch.abortus and Co.burnetti are potentially zoonotic, and advice regarding the risks posed to human health was given. Noteworthy is that neither diagnosis would have been made or pursued if the foetal membranes had not been submitted to the laboratory.

Insufficient colostral antibody absorption as evidenced by low Zinc sulphate turbidity (ZST) test readings was a common finding among neonatal calves submitted to all the RVLs. These calves were diagnosed with enteritis, interstitial pneumonia, septicaemia and peritonitis. Athlone noted an increased prevalence of infected navels with or without associated peritonitis, septicaemia and hypogammaglobulinaemia in young calves, emphasising the need to keep calf housing clean and to ensure early feeding of adequate colostrum.

Cryptosporidium and rotavirus continued to be the two main calf enteritis pathogens detected by the RVLs in February. Kilkenny and Limerick diagnosed several cases of salmonellosis in young calves during the month. Sudden death, high morbidity, diarrhoea and nervous signs were features of these cases.

Aspiration pneumonia, with evidence of milk in the trachea was diagnosed by Sligo in three calves from different farms. There was a history of stomach feeding in each case. Kilkenny diagnosed several cases of pneumonia in three month old calves.

Limerick diagnosed Infectious Bovine Rhinotracheitis (IBR) in a 13-month old bull from an outbreak of severe pneumonia with haemorragic tracheitis (20% morbidity) in a feedlot. Fascioliasis was diagnosed by Dublin in two nine-month-old calves in poor body condition, which had submandibular and abomasal oedema. Athlone isolated Arcanobacter pyogenes from a very large abscess in the wall of the heart of a 13 month old pedigree Charolais bull.

Limerick diagnosed Psoroptes ovis mange in a two-year old housed bullock that had a history of alopecia and scratching for over six-months (Figure 1). There had been no response to a topical ectoparasiticide. Herd mates were similarly affected. The owner was advised to treat the animals with two injections of doramectin (Dectomax, Pfizer Animal Health) given two-weeks apart. Although the primary case deteriorated and died within a few days, the other animals improved rapidly. This is a notifiable condition.

Limerick and Kilkenny found combined chronic fascioliasis and parasitic gastroenteritis individually and in a variety of animals with a history of ill thrift. Kilkenny also diagnosed Pasteurella multocida pneumonia in one such case.

Sligo diagnosed fibrinous reticuloperitonitis and pericarditis in a Friesian dairy cow with a history of bloat and grunting. Purulent pericarditis (bread and butter heart) was diagnosed by Limerick in a four-year old Friesian cow fed on a total mixed ration. Kilkenny diagnosed cardiac tamponade associated with traumatic reticulitis, in a young cow which had died suddenly (Figure2). A wire was found in the reticulum and its track through the diaphragm, pericardium and into the coronary vessel could be seen. Orpin and Harwood (2008) suggest fragments of wire from old tyres used to secure silage clamps are a common cause of traumatic reticulo-peritonitis in cattle. The use of TMR diets is also considered a potential risk factor.

Limerick isolated a pure growth of E. coli from the udder of a dairy cow with lesions of severe mastitis and cellulitis extending down the hind limbs. This was one of a small number of animals had developed severe coliform-type mastitis a few days after blanket dry cow therapy.

Dublin detected multiple liver abscesses protruding through the liver capsule and adhering to the diaphragm causing a localised peritonitis in a post-parturient downer cow.

Sligo diagnosed premature placental expulsion as the cause of stillbirth confined to heifers in a Galway dairy herd. No infectious or metabolic cause could be identified. Affected heifers tended to be slow about calving. The afterbirth emerged immediately after calving. This rapid expulsion of the placenta is a feature of premature placental separation and expulsion syndrome as described by Mee (1991). The premature separation is thought to lead to anoxia and foetal death. Foetal malposition is associated with the condition, but it is not established if this is causal or a consequence.

Cork diagnosed hypophosphataemia in 11 cows at pasture in a 130 cow dairy herd. Haemoglobinurea and anaemia were the presenting clinical signs.

Athlone isolated Salmonella typhimurium during an investigation into persistent scouring in suckler cows. A previous submission showed evidence of paraphistomum spp. infestation but dosing with oxyclosanide had not resolve the problem. The zoonotic risks of S. typhimurium were emphasised to the owner and herd veterinary surgeon.

Sheep

Toxoplasmosis was regularly identified as a cause of abortion in ewes by the various RVLs. Athlone, Dublin and Kilkenny cultured Salmonella dublin was cultured from aborted ovine foetuses in a number of outbreaks. Athlone considered prevalence of salmonella to be greater than usual in February. Dublin and Athlone also encountered outbreaks of enzootic abortion of ewes (EAE) (Figure 3).

Figure 3 Placenta from ewe that aborted due to Enzootic abortion of Ewes (photo William Byrne)

Multiple rib fractures along with large thoracic blood clots were found in two newborn lambs presented to Sligo from a flock where ten lambs had died. The lambs were large and the problem was confined to single lambs suggesting dystocia led to the deaths.

Suppurative polyarthritis due to Steptococcus dysgalactiae was diagnosed by Dublin in three week-old lambs, with a history of pyrexia, lameness, and swaying which lead to eventual recumbency. Twenty out of 200 lambs were affected. Limerick diagnosed coccidiosis in a three-week old lamb scouring for a few days before death. Limerick, Kilkenny and Sligo diagnosed clostridial enterotoxaemia in three to six week old lambs which had a history of sudden death.

Chronic fascioliasis continued to be a significant cause of death in adult ewes submitted to all the RVLs. Presenting signs included anaemia, weakness, staggering and sudden death after lambing. Severe ascites and oedema of the abomasal wall were observed in some cases.

Twin lamb disease was diagnosed in a number of ewes submitted to Sligo in February. Concurrent parasitic gastroenteritis was seen in one case. In another the ewes were on primarily a concentrate diet, with forage provided by the straw bedding material.

Avian

Limerick diagnosed lead poisoning in a swan found in a comatose state.

Dublin diagnosed peritonitis and hepatitis in four hens received from a layer flock.

Porcine

Salmonella typhimurium phage type U288 was isolated by Dublin from diptheritic caecum and large intestine lesions in two weaner pigs. This strain has been isolated from cases of diptheritic enteritis lesions in the caecum and colon of pigs on a number of occasions by the Veterinary Laboratories Agency (VLA) in the UK.

Other species

A faecal sample taken from a 25 year old circus camel with a history of diarrhoea and weight loss was found by Limerick to have a massive strongyle burden (>10,000 epg).